Currently, upper respiratory tract disease (URTD) and habitat loss are contributors to a decline in gopher and desert tortoise populations. And since these reptiles are keystone species—that is, the habitats they create are home to more than 300 other species—their population decline significantly affects the ecosystem. According to a recent study in Ecology, sexually-mature male tortoises were at the greatest risk of carrying and spreading URTD due in large part to their social behavior.